U.S. patent application number 12/412595 was filed with the patent office on 2009-07-16 for electrolyte additive for performance stability of batteries.
This patent application is currently assigned to Medtronic, Inc.. Invention is credited to Kaimin Chen, Donald R. Merritt, Craig L. Schmidt.
Application Number | 20090181302 12/412595 |
Document ID | / |
Family ID | 37991325 |
Filed Date | 2009-07-16 |
United States Patent
Application |
20090181302 |
Kind Code |
A1 |
Chen; Kaimin ; et
al. |
July 16, 2009 |
ELECTROLYTE ADDITIVE FOR PERFORMANCE STABILITY OF BATTERIES
Abstract
An organic additive to an electrolyte for a battery cell in an
implantable medical device is presented. At least one organic
additive is selected from a group comprising one of lithium
salicylate, hydroxyphthalic anhydride, a hydroxybenzoic acid,
salicylate ester, salicylamide, and salicylanilide.
Inventors: |
Chen; Kaimin; (New Brighton,
MN) ; Schmidt; Craig L.; (Eagan, MN) ;
Merritt; Donald R.; (Brooklyn Center, MN) |
Correspondence
Address: |
MUETING, RAASCH & GEBHARDT, P.A.
P.O. BOX 581336
MINNEAPOLIS
MN
55458-1336
US
|
Assignee: |
Medtronic, Inc.
Minneapolis
MN
|
Family ID: |
37991325 |
Appl. No.: |
12/412595 |
Filed: |
March 27, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11343323 |
Jan 31, 2006 |
|
|
|
12412595 |
|
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Current U.S.
Class: |
429/207 ;
429/188 |
Current CPC
Class: |
H01M 4/483 20130101;
H01M 6/168 20130101; H01M 4/54 20130101; H01M 2300/0037 20130101;
H01M 4/382 20130101; H01M 4/405 20130101; H01M 4/502 20130101 |
Class at
Publication: |
429/207 ;
429/188 |
International
Class: |
H01M 10/26 20060101
H01M010/26; H01M 6/04 20060101 H01M006/04 |
Claims
1-8. (canceled)
9. An implantable medical device comprising a battery comprising an
electrode assembly and an electrolyte, wherein the electrolyte
comprises a liquid electrolyte and a performance enhancing
additive, wherein the performance enhancing additive comprises an
organic compound comprising hydroxy and carboxy groups.
10. The implantable medical device of claim 9 wherein the electrode
assembly comprises an anode comprising an element selected from the
group of a Group IA element and a Group IIA element.
11. The implantable medical device of claim 10 wherein the anode
comprises material selected from the group of a Group IA metal, an
alloy thereof, and an intermetallic compound thereof.
12. The implantable medical device of claim 11 wherein the anode
comprises a Group IA element in metallic form.
13. The implantable medical device of claim 11 wherein the anode
comprises a Group IA element in ionic form.
14. The implantable medical device of claim 10 wherein the
electrode assembly comprises a lithium anode.
15. The implantable medical device of claim 9 wherein the liquid
electrolyte comprises a lithium salt, propylene carbonate, and
dimethoxyethane.
16. The implantable medical device of claim 9 wherein the electrode
assembly comprises a cathode comprising a metal oxide.
17. The implantable medical device of claim 16 wherein the cathode
comprises a metal oxide selected from the group of vanadium oxide,
silver vanadium oxide, manganese oxide, and lithium vanadium
oxide.
18. The implantable medical device of claim 9 wherein the electrode
assembly comprises a cathode comprising carbon monofluoride and a
hybrid thereof.
19. The implantable medical device of claim 9 wherein the battery
is a lithium carbon monofluoride silver vanadium oxide (Li/CFx-SVO)
battery.
20. The implantable medical device of claim 9 wherein the organic
compound comprises an aromatic hydroxycarboxylate-based
compound.
21. The implantable medical device of claim 20 wherein the
hydroxycarboxylate-based compound is selected from the group
consisting of lithium salicylate, ethyl salicylate, a
hydroxyphthalic anhydride, a hydroxyphthalic acid, a
hydroxyphthalic amide, a hydroxybenzoic acid, a hydroxybenzamide,
salicylate ester, salicylamide, and salicylanilide.
22. The additive of claim 21 wherein the compound is selected from
a group consisting of lithium salicylate, a hydroxyphthalic
anhydride, a hydroxybenzoic acid, salicylate ester, salicylamide,
and salicylanilide.
23. The implantable medical device of claim 9 wherein the organic
compound has the following structure: ##STR00014## and derivatives
thereof, wherein F.sub.2 represents a ZA group, wherein Z is an
atom selected from the group consisting of O, N, B, P, and Si, and
A is an atom selected from the group consisting of M, H, and R,
wherein M represents metals selected from the group consisting
essentially of Li, Na, and K, and R is an organic group.
24. The implantable medical device of claim 23 wherein A is H.
25. The implantable medical device of claim 23 wherein A is M.
26. The implantable medical device of claim 9 wherein the
performance enhancing additive comprises a mixture of different
organic compounds comprising hydroxy and carboxy groups.
27. The implantable medical device of claim 26 wherein the
performance enhancing additive comprises a first organic additive
being at least one of lithium salicylate, a hydroxyphthalic
anhydride, a hydroxybenzoic acid, salicylate ester, salicylamide,
and salicylanilide.
28. The implantable medical device of claim 27 wherein the
performance enhancing additive comprises a second organic additive
being at least one of lithium salicylate, a hydroxyphthalic
anhydride, a hydroxybenzoic acid, salicylate ester, salicylamide,
and salicylanilide.
29. The implantable medical device of claim 28 wherein the
performance enhancing additive comprises a third organic additive
combined with the first and the second organic additives, the third
organic additive being at least one of lithium salicylate, a
hydroxyphthalic anhydride, a hydroxybenzoic acid, salicylate ester,
salicylamide, and salicylanilide.
30. An implantable medical device comprising a battery comprising:
an electrode assembly comprising: an anode comprising an element
selected from the group of a Group IA element and a Group IIA
element; and a cathode comprising a metal oxide; a liquid
electrolyte comprising a performance enhancing additive, wherein
the performance enhancing additive comprises at least one organic
compound comprising hydroxy and carboxy groups.
31. An implantable medical device comprising a lithium carbon
monofluoride silver vanadium oxide (Li/CFx-SVO) battery comprising
a liquid electrolyte comprising a performance enhancing additive,
wherein the performance enhancing additive comprises at least one
aromatic hydroxycarboxylate-based compound.
Description
RELATED APPLICATION
[0001] This application is related to, and claims the benefit of,
U.S. patent application Ser. No. 10/876,003 filed Feb. 13, 2003
entitled "Liquid Electrolyte For An Electrochemical Cell,
Electrochemical Cell And Implantable Medical Device", which is
incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention generally relates to an
electrochemical cell and, more particularly, to an additive in an
electrolyte for a battery.
BACKGROUND OF THE INVENTION
[0003] Implantable medical devices (IMDs) detect, diagnose, and
deliver therapy for a variety of medical conditions in patients.
IMDs include implantable pulse generators (IPGs) or implantable
cardioverter-defibrillators (ICDs) that deliver electrical stimuli
to tissue of a patient. ICDs typically comprise, inter alia, a
control module, a capacitor, and a battery that are housed in a
hermetically sealed container. When therapy is required by a
patient, the control module signals the battery to charge the
capacitor, which in turn discharges electrical stimuli to tissue of
a patient.
[0004] The battery includes a case, a liner, and an electrode
assembly. The liner surrounds the electrode assembly to prevent the
electrode assembly from contacting the inside of the case. The
electrode assembly comprises an anode and a cathode with a
separator therebetween. In the case wall or cover is a fill port or
tube that allows introduction of electrolyte into the case. The
electrolyte is a medium that facilitates ionic transport and forms
a conductive pathway between the anode and cathode. An
electrochemical reaction between the electrodes and the electrolyte
causes charge to be stored on each electrode. The electrochemical
reaction also creates a solid electrolyte interphase (SEI) or
passivation film on a surface of an anode such as a lithium anode.
The passivation film is ionically conductive and prevents parasitic
loss of lithium. However, the passivation film increases internal
resistance which reduces the power capability of the battery. It is
desirable to reduce internal resistance associated with the
passivation film for a battery.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The present invention will become more fully understood from
the detailed description and the accompanying drawings,
wherein:
[0006] FIG. 1 is a cutaway perspective view of an implantable
medical device (IMD);
[0007] FIG. 2 is a cutaway perspective view of a battery in the IMD
of FIG. 1;
[0008] FIG. 3 is an enlarged view of a portion of the battery
depicted in FIG. 2 and designated by line 4.
[0009] FIG. 4 is a cross-sectional view of an anode and a
passivation film;
[0010] FIG. 5 is graph that compares performance between a
conventional battery cell and exemplary battery cell that includes
an additive to an electrolyte;
[0011] FIG. 6A is a lithium anode from a control cell after one
month of storage at 60.degree. C.;
[0012] FIG. 6B is a lithium anode from a cell containing an
additive after one month of storage at 60.degree. C.; and
[0013] FIG. 7 is a flow diagram for forming an electrolyte in a
battery.
DETAILED DESCRIPTION
[0014] The following description of embodiments is merely exemplary
in nature and is in no way intended to limit the invention, its
application, or uses. For purposes of clarity, the same reference
numbers are used in the drawings to identify similar elements.
[0015] The present invention is directed to an organic additive for
an electrolyte in lithium carbon monofluoride silver vanadium oxide
(Li/CFx-SVO) batteries. The additive stabilizes performance of the
battery during storage, thermal processing, and throughout
discharge. In one embodiment, the organic additive is characterized
by a hydroxy (--OH) and/or carboxy groups. Exemplary additives
include lithium salicylate, hydroxyphthalic anhydride, a
hydroxybenzoic acid, salicylate ester, salicylamide, and
salicylanilide. These additives enable batteries to exceed certain
performance and stability requirements.
[0016] FIG. 1 depicts an implantable medical device (IMD) 10 such
as implantable cardioverter-defibrillators. IMD 10 includes a case
50, a control module 52, a battery 54 (e.g. organic electrolyte
battery) and capacitor(s) 56. Control module 52 controls one or
more sensing and/or stimulation processes from IMD 10 via leads
(not shown). Battery 54 includes an insulator 58 disposed
therearound. Battery 54 charges capacitor(s) 56 and powers control
module 52.
[0017] FIGS. 2 and 3 depict details of an exemplary organic
electrolyte battery 54. Battery 54 includes a case 70, an anode 72,
separators 74, a cathode 76, a liquid electrolyte 78, and a
feed-through terminal 80. Cathode 76 is wound in a plurality of
turns, with anode 72 interposed between the turns of the cathode
winding. Separator 74 insulates anode 72 from cathode 76 windings.
Case 70 contains the liquid electrolyte 78 to create an ionically
conductive path between anode 72 and cathode 76. Electrolyte 78,
which includes an additive, serves as a medium for migration of
ions between anode 72 and cathode 76 during an electrochemical
reaction with these electrodes. Electrolyte 78 includes, for
example, LiPF.sub.6 in propylene carbonate (PC) and dimethoxyethane
(DME).
[0018] Anode 72 is formed of a material selected from Group IA, IIA
or IIIB of the periodic table of elements (e.g. lithium, sodium,
potassium, etc.), alloys thereof or intermetallic compounds (e.g.
Li--Si, Li--B, Li--Si--B etc.). Anode 72 comprises an alkali metal
(e.g. lithium, etc.) in metallic or ionic form. Cathode 76 may
comprise metal oxides (e.g. vanadium oxide, silver vanadium oxide
(SVO), manganese dioxide (MnO.sub.2), lithium vanadium oxide
(LiV3O8) etc.), carbon monofluoride and hybrids thereof (e.g.,
CF.sub.x+MnO.sub.2), combination silver vanadium oxide (CSVO) or
other suitable compounds.
[0019] Electrolyte 78 chemically reacts with anode 72 to form an
ionically conductive passivation film 82 on anode 72, as shown in
FIG. 4. Electrolyte 78 includes a base liquid electrolyte
composition and at least one performance enhancing additive
selected from Table 1 presented below. In another embodiment,
electrolyte 78 includes a base liquid electrolyte composition and
at least one performance enhancing additive selected from Table 2.
The base electrolyte composition typically comprises 1.0 molar (M)
lithium hexafluorophosphate (1-20% by weight), propylene carbonate
(40-70% by weight), and 1,2-dimethoxyethane (30-50% by weight). A
small amount (e.g. 0.05 M) of organic additive is combined with
electrolyte 78.
TABLE-US-00001 TABLE 1 List of exemplary organic additives
Exemplary additive compound (Chemical Name) Chemical Structure
Lithium salicylate ##STR00001## Ethyl salicylate ##STR00002##
4-Hydroxy benzoic acid ##STR00003## 4-Hydroxy benzamide
##STR00004## 3-Hydroxy benzoic acid ##STR00005## 2-Hydroxy phthalic
anhydride ##STR00006## 2-Hydroxy phthalic amide ##STR00007##
2-Hydroxy phthalic acid ##STR00008## 2-Hydroxy benzoic acid
##STR00009## Salicyl anilide ##STR00010##
[0020] Skilled artisans understand that additive compositions may
be mixed with the base electrolyte composition to increase
performance of battery 54. Additive compositions are formed by
selecting at least two additives from Table 1 and/or Table 2.
Effective additive compositions are based upon additives that
exhibit superior performance stabilizing characteristics of battery
54. Generally, each additive is combined with electrolyte 78
through dissolution or other suitable means.
[0021] The additives are based upon a chemical class referred to as
aromatic hydroxcarboxylates. There are two base compounds that form
the performance enhancing additives. The chemical structure for the
first base compound is as follows:
##STR00011##
where F1 represents a first group such as a hydroxy group (OH). The
chemical structure for the second base compound is as follows:
##STR00012##
where F2 represents a second group. The second group comprises ZA.
Z is defined as O, N, B, P, Si. A is defined as M, H, R where M
represents metals such as Li, Na, K and other suitable metals.
[0022] The present invention also includes derivatives of the first
or second base compounds. For example, one or more carboxy groups
may be added to one of the base compounds. Additionally, one or
more hydroxy groups may be added to one of the base compounds.
Furthermore, a combination of at least one or more carboxy groups
and at least one or more hydroxy groups may be added to one of the
base compounds. Still yet another derivative relates to
condensation products. Bis-(3-hydroxy benzoic anhydride) is an
exemplary condensation product.
[0023] Table 2 lists exemplary embodiments in which the position of
each group, represented by F1 and F2, are placed in different
positions relative to the carbon atom of a benzene compound. A
benzene compound includes six carbon atoms that are represented by
the symbols C1, C2, C3, C4, C5, and C6, as shown below:
##STR00013##
Skilled artisans understand that a variety of other combinations
exist in which F1 and F2 are repositioned. Table 2 may be
interpreted in at least two ways. First, a skilled artisan selects
a compound such as compound 1. For compound 1, F1 is located at C6
and F2 is located at C1. Alternatively, a skilled artisan may
select the position of F1 and F2 to determine the type of
compound.
TABLE-US-00002 TABLE 2 Exemplary performance enhancing additives in
which groups F1 and F2 change their positions along a benzene ring
C1 C2 C3 C4 C5 C6 Compound atom atom atom atom atom atom 1 F1 0 0 0
0 0 1 2 F1 0 0 0 0 1 0 3 F1 0 0 0 1 0 0 4 F1 0 0 1 0 0 0 5 F1 0 1 0
0 0 1 6 F1 1 0 0 0 0 0 1 F2 1 0 0 0 0 0 2 F2 0 1 0 0 0 0 3 F2 0 0 1
0 0 0 4 F2 0 0 0 1 0 0 5 F2 0 0 0 0 1 0 6 F2 0 0 0 0 0 1
[0024] FIG. 5 graphically depicts the superiority of electrolyte 78
over a control electrolyte 88. Electrolyte 78 includes lithium
salicylate as the organic additive and the base electrolyte
composition previously described. Control electrolyte 88 is the
base electrolyte composition without any additive. Passivation
layer 82 initially possesses similar discharge to passivation layer
formed by control electrolyte 88. However, beginning in the
discharge (BOL), the passivation layer formed by control
electrolyte 88 exhibits resistance that substantially increases. In
contrast, electrolyte 78 that includes the additive causes battery
54 to exhibit increased performance and resistance that remains
substantially below the resistance of control electrolyte 88 late
in discharge. For example, electrolyte 78 results in battery 54
having 30 ohms lower resistance than control electrolyte 88, as
show in FIG. 5.
[0025] FIGS. 6A-6B illustrate the significant difference between a
lithium anode of a control battery cell 100 to a lithium anode from
a battery cell 110 containing an additive after one month of
storage at 60.degree. C. Lithium anode 110 with the additive is a
lighter shade of gray than the lithium anode 100 of a control
battery cell. A lighter shade indicates less oxidation occurred
which, in turn, produces a decreased amount of a passivation layer
82 compared to a conventional lithium anode 100.
[0026] FIG. 7 depicts a method for forming an organic additive
composition, which is later added to an electrolyte composition. At
operation 200, a first organic additive is selected. At operation
210, the first organic additive is combined with a second organic
additive to create an organic additive composition.
[0027] The following patent application is incorporated by
reference in its entirety. Co-pending U.S. patent application Ser.
No. ______, entitled "RESISTANCE-STABILIZING ADDITIVES FOR
ELECTROLYTE", filed on Jan. 31, 2006 by Donald Merritt and Craig
Schmidt and assigned to the same Assignee of the present invention,
describes resistance-stabilizing additives for electrolyte.
Although various embodiments of the invention have been described
and illustrated with reference to specific embodiments thereof, it
is not intended that the invention be limited to such illustrative
embodiments. For example, while an additive composition is
described as a combination of two additives, it may also include
two or more additives selected from Table 1. The description of the
invention is merely exemplary in nature and, thus, variations that
do not depart from the gist of the invention are intended to be
within the scope of the invention. Such variations are not to be
regarded as a departure from the spirit and scope of the
invention.
* * * * *